Electro-hydraulic control system for an automatic transmission

Abstract

An electro-hydraulic control system for a multiple speed automatic motor vehicle transmission includes main and auxiliary hydraulic pumps, a line pressure regulator, a lubrication pressure regulator, a lubrication override control valve and a torque converter control valve which is controlled by a variable force solenoid (VFS). Driver commands are provided to the system through a manual logic or spool valve which functions in conjunction with a spool or logic default valve and a default solenoid. Five solenoid valves receive various flows of hydraulic fluid and supply them to hydraulic actuators that engage and disengage four friction clutches and a selectable one-way clutch.

What is claimed is: 
     
       1. A control system for an automatic transmission comprising, in combination,
 a first hydraulic pump having an output, 
 a second hydraulic pump having an output, 
 a feed limit valve in fluid communication with said output of said second hydraulic pump and having an output, 
 a torque converter control valve in fluid communication with said output of said first hydraulic pump and having a control port and an output, 
 a torque converter apply solenoid valve having a first output in fluid communication with said control port of said torque converter control valve and a second output adapted to engage a lockup clutch of a torque converter, 
 a lubrication flow regulator valve having a first control port in fluid communication with said output of said first hydraulic pump and a second control port, 
 an oil cooler operably disposed between an outlet port of said torque converter control valve and an inlet port of said lubrication flow regulator valve, 
 a lubrication override enable valve having an outlet in fluid communication with said second control port of said lubrication flow regulator valve, 
 a manually operated spool valve having a first output enabling reverse and a second output enabling forward gears of such transmission, 
 a default control valve having inlet ports in fluid communication with said second output of said manually operated spool valve, a first default valve control port in fluid communication with said first output of said manually operated valve and a second default valve control port, 
 a default solenoid valve having an output in fluid communication with said second default valve control port of said default control valve, and 
 a plurality of solenoid valves, each of said solenoid valves having an inlet in fluid communication with said output of said second hydraulic pump and an output in fluid communication with a hydraulic clutch actuator. 
 
     
     
       2. The control system of  claim 1  wherein said manually operated valve includes a gear shift selector moveable by a vehicle operator and said default control valve is a two position valve. 
     
     
       3. The control system of  claim 1  further including a clutch solenoid valve having an output, a clutch enable valve having an inlet in fluid communication with said output of said clutch solenoid valve, an outlet and a control port in fluid communication with said output of said default solenoid and said output of said clutch enable valve through a three way check valve, and a double acting hydraulic piston and cylinder assembly having a first inlet in fluid communication with said output of said clutch enable valve and said first default valve control port through a three way check valve. 
     
     
       4. The control system of  claim 3  further including a selectable one-way clutch acted upon by said double acting hydraulic piston and cylinder assembly. 
     
     
       5. The control system of  claim 1  further including a variable bleed solenoid valve having an output in fluid communication with a control port of said pressure regulator valve. 
     
     
       6. The control system of  claim 1  wherein second hydraulic pump is electrically driven. 
     
     
       7. The control system of  claim 1  further including a hydraulic line from a port of said lubrication flow regulator valve for providing hydraulic fluid to a plurality of clutches. 
     
     
       8. An electro-hydraulic control system for an automatic transmission comprising, in combination,
 a source of pressurized hydraulic fluid, 
 a feed limit valve in fluid communication with said source of hydraulic fluid and having an output, 
 a torque converter control valve in fluid communication with said source of pressurized hydraulic fluid and having a control port and an output, 
 a torque converter apply solenoid valve having a first output in fluid communication with said control port of said torque converter control valve and a second output adapted to engage a lockup clutch of a torque converter, 
 a lubrication flow regulator valve having a first control port in fluid communication with said source of hydraulic fluid and a second control port, 
 a lubrication override enable valve having an outlet in fluid communication with said second control port of said lubrication flow regulator valve, 
 a manually operated valve having a first output enabling reverse and a second output enabling forward gears of such transmission, 
 a default control valve having inlet ports in fluid communication with said second output of said manually operated spool valve, a first default valve control port in fluid communication with said first output of said manually operated valve and a second default valve control port, 
 a default solenoid valve having an output in fluid communication with said second default valve control port, 
 a clutch solenoid valve having an output, 
 a clutch enable valve having an inlet in fluid communication with said output of said clutch solenoid valve, an outlet and a control port in fluid communication with said output of said default solenoid and said output of said clutch enable valve through a three way check valve, 
 a double acting hydraulic piston and cylinder assembly having a first inlet in fluid communication with said output of said clutch enable valve and said first default valve control port through a three way check valve, and 
 a plurality of solenoid valves, each of said solenoid valves having an inlet in fluid communication with said source of hydraulic fluid and an output in fluid communication with a hydraulic clutch actuator. 
 
     
     
       9. The electro-hydraulic control system for an automatic transmission of  claim 8  wherein said source of hydraulic fluid includes a first mechanically driven pump and a second electrically driven pump. 
     
     
       10. The electro-hydraulic control system for an automatic transmission of  claim 8  wherein said default control valve is a two position valve. 
     
     
       11. The electro-hydraulic control system for an automatic transmission of  claim 8  further including a selectable one-way clutch acted upon by said double acting hydraulic piston and cylinder assembly. 
     
     
       12. The electro-hydraulic control system for an automatic transmission of  claim 8  further including a variable bleed solenoid valve having an output in fluid communication with a control port of said pressure regulator valve. 
     
     
       13. The electro-hydraulic control system for an automatic transmission of  claim 8  further including a sump for receiving and storing hydraulic fluid. 
     
     
       14. The electro-hydraulic control system for an automatic transmission of  claim 8  further including a hydraulic fluid cooler disposed in fluid communication between an outlet of said torque converter control valve and an inlet of said lubrication flow regulator valve. 
     
     
       15. An electro-hydraulic control system for an automatic transmission comprising, in combination,
 a source of pressurized hydraulic fluid, 
 a feed limit valve in fluid communication with said source of hydraulic fluid and having an output, 
 a torque converter control valve in fluid communication with said source of hydraulic fluid and having a control port and an output, 
 a torque converter apply solenoid valve having a first output in fluid communication with said control port of said torque converter control valve and a second output adapted to engage a lockup clutch of a torque converter, 
 a lubrication flow regulator valve having a first control port in fluid communication with said source of hydraulic fluid and a second control port, 
 a lubrication override enable valve having an outlet in fluid communication with said second control port of said lubrication flow regulator valve, 
 a manually operated valve having a first output enabling reverse and a second output enabling forward gears of such transmission, 
 a default control valve having inlet ports in fluid communication with said second output of said manually operated spool valve, a first default valve control port in fluid communication with said first output of said manually operated valve and a second default valve control port, 
 a default solenoid valve having an output in fluid communication with said second control port and 
 a plurality of solenoid valves, each of said solenoid valves having an inlet in fluid communication with said source of hydraulic fluid and an output in fluid communication with a hydraulic clutch actuator. 
 
     
     
       16. The electro-hydraulic control system for an automatic transmission of  claim 15  wherein said source of hydraulic fluid includes a first mechanically driven pump and a second electrically driven pump. 
     
     
       17. The electro-hydraulic control system for an automatic transmission of  claim 15  wherein said manually operated valve includes a gear shift selector moveable by a vehicle operator and said default control valve is a two position valve. 
     
     
       18. The electro-hydraulic control system for an automatic transmission of  claim 15  further including a pressure regulator valve operably disposed between said source of pressurized hydraulic fluid and said torque converter control valve. 
     
     
       19. The electro-hydraulic control system for an automatic transmission of  claim 15  further including a hydraulic fluid cooler disposed in fluid communication between an outlet of said torque converter control valve and an inlet of said lubrication flow regulator valve. 
     
     
       20. The electro-hydraulic control system for an automatic transmission of  claim 15  further including a clutch solenoid valve having an output, a clutch enable valve having an inlet in fluid communication with said output of said clutch solenoid valve, an outlet and a control port in fluid communication with said output of said default solenoid and said output of said clutch enable valve through a three way check valve, a double acting hydraulic piston and cylinder assembly having a first inlet in fluid communication with said output of said clutch enable valve and said first default valve control port through a three way check valve and a selectable one-way clutch acted upon by said double acting hydraulic piston and cylinder assembly.